2006 Tundra that is blowing coolant out overflow.

Sure sounds like a blown headgasket putting too much pressure into the cooling system, but I have also seen a partially plugged radiator do the same thing. so did the shop test for blown headgaskets and do a flow test on the cooling system?

Does it only blow coolant when you shut off the engine? If so you need to check the ignition timing first. You could have a bad knock sensor that's causing the computer to severely retard the ignition timing. Or if you have a valve tap the knock sensor may be picking it up and retarding the ignition timing unnecessarily. You could also have a worn timing chain that is retarding the valve timing. This will cause the cooling system to boil over when you shut off the engine as well. Hope that helps! Jim

The dealer said probably blown head gasket but when they checked they could not find a issue. They pressure tested the cylinders. They did say that it might be so small the reason they could not detect it. It generally only blows fluid after a longer trip. New radiator 50k miles ago, The timing chain has been changed twice and is due in about 20k but dealer said it was fine. The truck never overheats I'm sure the fluid is over pressured. It is flowing past a new radiator cap.

To check for a blown head gasket you can get a cooling system pressure tester. With the engine cold pressurize the cooling system. Start the engine and look at the needle on the pressure tester gauge. If it bounces, the head gasket is blown. Hope that helps! Jim